The Ga1α1,3Ga1 epitope has received considerable attention stemming from its presence in glycoproteins of most mammals and its conspicuous absence in humans, apes, and Old World monkeys. The loss is attributable to frameshift mutations in α,3-galactosyltransferase and the resulting immunogenicity of the epitope is a significant barrier to xenotransplantation.
There are a few proteins that bind the Ga1α,3Ga1 epitope. For example, antibodies which recognize the α-galactosyl epitope and Clostridium difficile toxin A both bind well to some Ga1α1,3Ga1-containing sugars. However, merely binding to this epitope is not useful if the same protein binds many other related epitopes.
What is needed is a protein which binds the Ga1α1,3Ga1 epitope with specificity so that it can be useful in binding assays, including diagnostic assays.